Radson fault code E9
Fault code E9 on a Radson boiler (including Radostar) means: The overheating protection (12) of the heat exchanger is activated when the temperature rises above 105C. Reset the appliance once. If the code comes back, a part is usually faulty. You can check the water pressure and settings yourself; leave work on gas-carrying parts to a certified gas engineer.
After a safety alert (gas, flue gas, combustion), reset no more than once and call in a certified gas engineer. If you smell gas, call your national gas emergency number or 112 immediately.
Cause
Fault code E9 on a Radson boiler indicates: The overheating protection (12) of the heat exchanger is activated when the temperature rises above 105C.
Fixing fault code E9: step by step
- Read the water pressure on the display or gauge. With the system cold it should be between 1.5 and 2 bar.
- Bleed the radiators with a radiator key, then check the pressure again and top up if needed.
- Check that the radiator valves and underfloor heating circuits are open, so the water can circulate.
- Reset the appliance once. If the code comes straight back, do not keep resetting it.
- If the fault keeps returning, or the boiler gurgles or knocks, the heat exchanger may be fouled. Flushing or replacing it is work for a qualified heating engineer.
Applies to
Radson Radostar, EHLE 23, EHLE 27, EHLE 34, EHLE 39, EHLE 78, EHLE 17.
Click a model for the parts list and exploded view of that appliance.
Fault code E9 on other Radson series
The same code does not mean the same thing on every series. Check the rating plate to see which series you have:
- E9 on Maxicom, NL / E: Maximum thermostat. Open contact.
Matching parts
Radson parts are available from Instalpunt; shipping to EU countries from €12.95 (€16.95 for more distant countries), usually 3–5 working days.
For fault code E9, the part involved is usually in the category: heat exchanger.
This message does not point directly to one faulty part. These are the parts that most often fit this appliance:
- Bosch gasket for e.g. EHLE 23 87168336790 € 26.51
- Nefit maximum thermostat Clixon € 33.98
- Bosch plug for NTC € 33.98
Fix it yourself or call an engineer?
Always consult the manual for your appliance and work safely. If in doubt or if the fault comes back, call in a qualified professional. A question about a part? Write to us at info@instalpunt.nl.
Frequently asked questions
What does Radson boiler fault code E9 mean?
The overheating protection (12) of the heat exchanger is activated when the temperature rises above 105C..
How do I fix fault code E9 on a Radson boiler?
First check the cause described above. Then restart the appliance using the reset button. If the message comes back, a part usually needs replacing or the fault needs to be repaired by a qualified professional.
Which parts do I need for Radson fault code E9?
That depends on the exact cause. In the Radson parts overview at Instalpunt you will find the current price and stock for each part.
Can I fix fault code E9 myself?
You can reset the appliance and check things like the water pressure or settings yourself. Work on gas-carrying parts must be left to a certified gas engineer.
All Radson boiler faults and codes at a glance →